Typhoon Storm Research Articles

Numerical Simulation of Typhoon Storm Surge in Wenzhou Coastal Areas

Focusing on the numerical simulation of storm surge in the coastal waters of Wenzhou, this paper uses the atmospheric Mesoscale Model5 (MM5) model to provide the wind field of typhoons, and the advanced circulation (ADCIRC) model for oceanic, coastal, and estuarine waters to simulate the process of storm surges, which adopts the finite element method with a dry-wet grid. The simulated results agree well with the observed data from marine observation stations (Longwan, Aojiang, Ruian), indicating that the simulation of storm surge is accurate. The good agreement between the simulated and observed results of four typhoons (Nos. 200216, 200414, 200509, 200608) shows that the combination of the two numerical models has the capacity to calculate storm surge elevations along the coast of Wenzhou. Using this method to simulate the 23 typhoon storm surge processes of the Wenzhou sea area of the last 23 years, we find that the majority of storm surge is between 0.5 to 2.5 m, and about one-fifth have an extreme value of more than 2 m. The maximum storm surge value recorded in Wenzhou coastal waters is 3.02 m, which occurred during Typhoon Wipha (No. 200713) at 03:00 on September 19, 2007 when landed. Water decreasing processes occurred 10 h after the main water increasing process with the maximum negative storm surge of -0.5 m. This paper can be used as a reference for storm surge forecasting, coastal engineering design and damage minimization in the future.

Revealing the impact of storm surge on taxi operations: Evidence from taxi and typhoon trajectory data

Storm surges are one of the most destructive natural ocean disasters in the world, which pose a great threat to economic development, public safety, and transport in coastal cities. Investigating the response of urban traffic conditions during storm surges and discovering sensitive urban areas are crucial to urban planning, disaster prevention, and emergency rescue. Therefore, this study investigates the impact of typhoons on taxi operations to target sensitive areas of the city. In this study, the change in taxi service operation in Shenzhen during typhoon storm surges from 2012 to 2014 was explored at the city district scale using a diverse set of data including taxi trajectory data, typhoon track data, and tide level data. Several aspects were included to access this impact, for example the number of daily orders per taxi, the trip length, the degree of closeness to the typhoon-affected area, the coverage area of the taxi service, and the spatial dynamics of the origin and destination matrix. The regular trend and correlation of storm surge elements and taxi parameters were first analyzed. The distribution of the taxi trajectory data was then used to detect variations in the service area, and the reasons for these variations were discussed. The result shows that storm surges with diverse characteristics do affect taxi operations to differing degrees, and that there was a potential correlation between tide level and taxi service area. The sensitive areas for taxis during typhoon storm surges were mainly located at the boundary between the central urban area and other districts of Shenzhen, they were constrained by the dynamic changes in the origins and destinations, and they were likely related to important transportation hubs in the city. This finding provides a reference to support disaster prevention preparedness and decision-making by local authorities.

Retrieval of coastal typhoon storm surge using multi-GNSS-IR

Retrieval of coastal typhoon storm surge using multi-GNSS-IR

Evaluation of the WRF physical parameterisations for Typhoon rainstorm simulation in southeast coast of China

Due to easily causing severe disasters in mountainous areas, typhoon rainfall forecast with numerical weather prediction (NWP) system plays an important role for meteorological and hydrological use. In order to investigate the applicability of physical parameterisations for typhoon rainstorms, thirty-six physical parameterisation combinations are designed by three microphysics (Lin, WSM6 and WDM6), three pairs of longwave/shortwave radiations (RRTM/Dudhia, RRTMG/RRTMG and CAM/CAM) and four cumulus parameterisations (KF, BMJ, GD and Grell 3D). The Weather Research and Forecasting (WRF) model is used to simulate the three representative typhoon storm events occurred in southeast coast of China and the rainfall simulations in Meixi catchment are evaluated. Not only for the individual parameterisation but also for the parameterisation combination, WSM6, RRTMG/RRTMG and KF outperform the other physical parameterisation as a whole. The WRF model has poor capability in simulating the rainfall caused by strong convection, and the storm events with uneven distributed rainfall tend to have worse rainfall simulation in space and time dimensions. The findings provide references for choosing the physical parameterisation, which can help to obtain relatively reliable typhoon rainfall forecast and flood warning in catchment scale. The shortage of the NWP system and the solution for improve the rainfall simulation are also put forward.

Study on Risk Assessment of Typhoon Storm Surge Based on Public Safety Triangle Theory

Based on the “triangle theory” of public safety and combined with the formation mechanism and characteristics of storm surge disasters, this research comprehensively considered the danger of disaster events, disaster carriers in the affected area, and disaster prevention and mitigation capabilities such as emergency management and considered the possibility of secondary/derived disasters arising from disaster factors and whether they are in sensitive time periods with a view to studying the risk evaluation technology of storm surge disasters. According to this study, a risk assessment method is established to assess the risk of real-time dynamic events before emergency decision-making.

Typhoon storm surge ensemble forecast based on GPU technique

The accuracy of typhoon forecasts plays an important role in the prediction of storm surges. The uncertainty of a typhoon’s intensity and track means it is necessary to use an ensemble model to predict typhoon storm surges. A hydrodynamic model, which is operational at the National Marine Environmental Forecasting Center, is applied to conduct surge simulations for South China coastal areas using the best track data with parametric wind and pressure models. The results agree well with tidal gauge observations. To improve the calculation efficiency, the hydrodynamic model is modified using CUDA Fortran. The calculation results are almost the same as those from the original model, but the calculation time is reduced by more than 99%. A total of 150 typhoon cases are generated by combining 50 typhoon tracks from the European Centre for Medium-Range Weather Forecasts with three possible typhoon intensity forecasts. The surge ensembles are computed by the improved hydrodynamic model. Based on the simulated storm surges for the different typhoon cases, ensemble and probability forecast products can be provided. The mean ensemble results and probability forecast products are shown to agree well with the observed storm surge caused by Typhoon Mangkhut. The improved model is highly suitable for ensemble numerical forecasts, providing better forecast products for decision-making, and can be easily implemented to run on regular workstations.

Study on the decision-making behavior of evacuation for coastal residents under typhoon storm surge disaster

Storm surge is one kind of meteorological tides which may cause serious destruction on coastal facilities. In the past, large death tolls have resulted from the rise of the ocean associated with many of the major typhoons that have made landfall. Although evacuation has been recognized as an effective protective action in responding to a typhoon emergency, it is still not clear why some people leave but others do not. Thus, it is important to identify which factors govern the behavior of at risk people on evacuation decision. The empirical work presented in this paper is the result of an original survey. The survey was designed to understand coastal resident's possible evacuation decision under alternate typhoon storm surge scenarios. The investigative team conducted surveys with evacuees to learn about the geophysical and social influences that had factored in their decision to evacuate. We obtained the basic information of coastal residents under typhoon storm surge disaster zone through questionnaire and interview. Based on the investigation and analysis, the analysis of these factors are summarized as follows: Demographic characteristics of the participants, disaster cognitive factors, the consideration of evacuation decision-making, the choice of evacuation site, evacuation behavior factors. A binary logistic regression analysis was performed, which resulted in an effective empirical model for evacuation behavior of coastal residents. This paper identified several independent variables whose effects on evacuation might interact with the effect of coastal residents. This result not only offers a strategy for improving disaster prevention, but also provides policy-makers with some insights to intensify and improve emergency plan of preventing typhoon storm surge.

Future Interactions Between Sea Level Rise, Tides, and Storm Surges in the World's Largest Urban Area

AbstractThe Pearl River Delta contains the world's largest urban area in both size and population. It is a low‐lying flood‐prone coastal environment exposed to sea level rise (SLR) and extreme water levels caused by typhoons. A Finite Volume Community Ocean Model implementation for the South China Sea and the Pearl River Delta is used to understand how future SLR, tides, and typhoon storm surges will interact and affect coastal inundation. The SLR signal and extreme surge levels provide the major contributions to flooding; however, amplification of tides could exceed 0.5 m for 2.1 m SLR and should be considered when planning future coastal defences. On the other hand, if typhoons like Hato or Mangkhut, the latest and strongest ones hitting the area, were to happen in the future, a surge level reduction up to 0.5 m could be expected in coastal areas.

The impact of different historical typhoon tracks on storm surge: A case study of Zhejiang, China

Abstract A typhoon-induced storm surge simulation system was developed for the Zhejiang coast consisting of an assimilation wind-pressure model and the ADCIRC+SWAN model. The simulated peak and phase of the storm surge were found to match the observed data very well. We discussed the sensitivity of the modeled storm surge to changes in the computational domain, and compared the simulation results from the assimilation wind-pressure model and the symmetric Holland model. The sensitivity of 23 newly-constructed typhoon tracks to the Wenzhou City storm surge was investigated using the validated storm surge simulation system. The storm surges vary significantly when the typhoon tracks are at different positions relative to the station. Given this, the impacts of 55 historical tracks from 1951 to 2017 on the coast of Zhejiang Province were simulated and analyzed. Although the typhoon tracks with no landfall on China's eastern mainland posed a threat to the entire Zhejiang coast, the tracks making landfall at Fujian were most likely to cause a storm surge in Wenzhou City, Zhejiang Province. The results of this study will help to increase the understanding of typhoon storm surge along China's coastal areas and may serve as reference material in studies of disaster reduction and prevention techniques in the Zhejiang region.

Study on methods to identify the impact factors of economic losses due to typhoon storm surge based on confirmatory factor analysis

By establishing an objective and effective indicator system, we can accurately estimate the economic losses inflicted by typhoon storm surge. With Guangdong selected as the area for our case study, we used confirmatory factor analysis to identify and select three types of risk factors generating economic losses from such disasters: hazard, vulnerability, and disaster resilience. Moreover, by dividing the study area into three time periods in based on economic development conditions, we analyzed the indicator changes in various risk factors within them. Studies have shown that impact indicators from various risk factors at different time periods have not changed significantly, while their degree of relevance has varied with each risk factor. Compared with the traditionally established indicator systems, the basic indicators based on historical cases in this paper are more factual, and the application of confirmatory factor analysis in the selection of indicators has eliminated the interference of subjective factors, rendering the results more rational and scientific.

Jason-1 Observation of Typhoon Storm Surge and Analysis Based on Numerical Simulation

Storm surge is one of the most disastrous marine disasters to coastal regions. It is greatly essential to research on storm surge and mitigate this damage. In our paper, Typhoon hit the Japan Coast on 31 July, 2004. Jason-1 and two tide-gauge stations all captured the obvious sea level anomalies. The magnitude of this storm surge was approximately 0.4 m. We further used the Unstructured Grid Finite-Volume Community Ocean Model (FVCOM) to simulate this storm surge. The method based on the relationships between the maximum wind speed of best track and that of CFSR data was adopted to reconstruct wind field. This method reduced the root mean squared error (RMSE) from 0.11 m to 0.07 m at Owase station. The accuracy was improved by 35%. Similar to Owase station, the RMSE was reduced from 0.085 m to 0.06 m at Cape Muroto station. The accuracy was improved by 30%.

Influence of Tropical Cyclone Intensity and Size on Storm Surge in the Northern East China Sea

Typhoon storm surge research has always been very important and worthy of attention. Less is studied about the impact of tropical cyclone size (TC size) on storm surge, especially in semi-enclosed areas such as the northern East China Sea (NECS). Observational data for Typhoon Winnie (TY9711) and Typhoon Damrey (TY1210) from satellite and tide stations, as well as simulation results from a finite-volume coastal ocean model (FVCOM), were developed to study the effect of TC size on storm surge. Using the maximum wind speed (MXW) to represent the intensity of the tropical cyclone and seven-level wind circle range (R7) to represent the size of the tropical cyclone, an ideal simulation test was conducted. The results indicate that the highest storm surge occurs when the MXW is 40–45 m/s, that storm surge does not undergo significant change with the RWM except for the area near the center of typhoon and that the peak surge values are approximately a linear function of R7. Therefore, the TC size should be considered when estimating storm surge, particularly when predicting marine-economic effects and assessing the risk.

Numerical simulations and comparative analysis for two types of storm surges in the Bohai Sea using a coupled atmosphere-ocean model

The Bohai Sea is extremely susceptible to storm surges induced by extratropical storms and tropical cyclones in nearly every season. In order to relieve the impacts of storm surge disasters on structures and human lives in coastal regions, it is very important to understand the occurring of the severe storm surges. The previous research is mostly restricted to a single type of storm surge caused by extratropical storm or tropical cyclone. In present paper, a coupled atmosphere-ocean model is developed to study the storm surges induced by two types of extreme weather conditions. Two special cases happened in the Bohai Sea are simulated successively. The wind intensity and minimum sea-level pressure derived from the Weather Research and Forecasting (WRF) model agree well with the observed data. The computed time series of water level obtained from the Regional Ocean Modeling System (ROMS) also are in good agreement with the tide gauge observations. The structures of the wind fields and average currents for two types of storm surges are analyzed and compared. The results of coupled model are compared with those from the uncoupled model. The case studies indicate that the wind field and structure of the ocean surface current have great differences between extratropical storm surge and typhoon storm surge. The magnitude of storm surge in the Bohai Sea is shown mainly determined by the ocean surface driving force, but greatly affected by the coastal geometry and bathymetry.

Characteristics of Heavy Storms and the Scaling Relation with Air Temperature by Event Process-Based Analysis in South China

The negative scaling rate between precipitation extremes and the air temperature in tropic and subtropic regions is still a puzzling issue. This study investigates the scaling rate from two aspects, storm characteristics (types) and event process-based temperature variations. Heavy storms in South China are developed by different weather systems with unique meteorological characteristics each season, such as the warm-front storms (January), cold-front storms (April to mid-May), monsoon storms (late May to June), convective storms, and typhoon storms (July to September). This study analyzes the storm characteristics using the hourly rainfall data from 1990 to 2017; compares the storm hyetographs derived from the one-minute rainfall data during 2008–2017; and investigates the interactions between heavy storms and meteorological factors including air temperature, relative humidity, surface pressure, and wind speed at 42 weather stations in Guangzhou during 2015–2017. Most storms, except for typhoon and warm-front storms, had a short duration (3 h) and intense rates (~13 mm/h) in Guangzhou, South China. Convective storms were dominant (50%) in occurrence and had the strongest intensity (15.8 mm/h). Storms in urban areas had stronger interactions with meteorological factors and showed different hyetographs from suburban areas. Meteorological factors had larger variations with the storms that occurred in the day time than at night. The air temperature could rise 6 °C and drop 4 °C prior to and post-summer storms against the diurnal mean state. The 24-h mean air temperature prior to the storms produced more reliable scaling rates than the naturally daily mean air temperature. The precipitation extremes showed a peak-like scaling relation with the 24-h mean air temperature and had a break temperature of 28 °C. Below 28 °C, the relative humidity was 80%–100%, and it showed a positive scaling rate. Above 28 °C, the negative scaling relation was likely caused by a lack of moisture in the atmosphere, where the relative humidity decreased with the air temperature increase.

Web GIS Based Typhoon Committee Disaster Information System for Typhoon Disaster Risk Management

ABSTRACT Out of damage from natural disasters in recent decade, more than 60% is due to typhoon in Korea, and yearly damage has exceeded 10 billion USD as urbanization and development continue. Many local areas are affected by climate extremes such as typhoons and flash flood and great amount of coastal areas are exposed to flood risk by typhoon related winds and storm surges. These climatic impacts are expected to be severer and eventually impede development of the region. The main reasons for the high vulnerability to natural disaster are that great number of local cities are located in low land and vulnerable region and highly populated. As a scientific effort on disaster prevent and disaster risk reduction, statistical estimations of risk and regional vulnerability have been carried out. Typhoon trajectory is estimated from statistically method to determine the typhoon approaching region of interest and risk is also estimated from physical modeling of rainfall rate and wind speed, while regional vulnerability is statistically modeled from damage data of properties. This paper describes the development of typhoon risk assessment and application to Asia countries including Republic of Korea using Web GIS based technology. The system would be able to help decision makers to take informed actions during emergency situations of an approaching tropical cyclone.

FUTURE CLIMATE EXPERIMENTS ON INTENSITY AND STORM SURGE OF TYPHOON SANBA (2012)

The recent progress of the global warming raise concerns the future changes of tropical cyclones (i.e. hurricane, typhoon, and cyclone) and their associated coastal disasters. It is thought that the increases of both the sea surface temperature and ocean heat contents by the global warming could increase the intensity of future tropical cyclones. As a method of quantitative assessment for the impact of global warming on tropical cyclones and their storm surges, “pseudo-global warming downscaling” is generally adopted using a regional climate model and a storm surge model (Takayabu et al., 2015). Estimating the differences of experiments between present and future climate, we can quantify the future changes of typhoon intensity and storm surge by the global warming. Using the high-resolution typhoon model, we carry out a present climate experiment and pseudo-global warming experiments on typhoon intensity and its storm surge of Typhoon Sanba (2012) in this study. Sanba went northward on the west coast of Kyushu Island and caused a storm surge in Ariake Sea, Japan. Sanba had a minimum central pressure of 900 hPa and a maximum wind speed of 55 m/s. The observed maximum sea level anomaly was 104 cm at Oura, Saga Prefecture. To evaluate the impacts of global warming differences (GWDs) on typhoon intensity and storm surge, sensitivity experiments on different months (August, September, and October) in future typhoon season are also made.

ECO-SYSTEM BASED BEACH EROSION CONTROL BY BERM NOURISHMENT COMBINED WITH BURIED SAND TUBE

Miyazaki Coast is a 10 km stretch sandy beach between the Miyazaki Port and the Hitotsuse River, located south of Japan facing the Pacific Ocean. Significant beach erosion has been observed owing to the entrapment of sand in the harbor area and the blockage of longshore sand transport by the river mouth jetties. Sato et al. (ICCE 2010) estimated that the direction of the long-term longshore sand transport is to the southward on the basis of thermo-luminescence measurement of beach sediments. Continuous bathymetry surveys indicated the southward longshore sand transport rate at 200 thousand m3/year. However, a large variability of the incident wave direction suggested the variability in the direction of the longshore transport. Occasional attacks of typhoon storms appeared to accelerate the erosion. As a countermeasure to mitigate the erosion, sand nourishment has been introduced since 2008 with the amount of 50 to 80 thousand m3/year. Three groins were constructed to decrease the longshore transport. However, further erosion has been observed by typhoon storms even on the nourished area. This paper describes the results of on-site monitoring of waves, currents and topography change to understand the role of typhoon storms in beach erosion and to investigate the performance of eco-system based erosion control works.

Shifts in stream hydrochemistry in responses to typhoon and non-typhoon precipitation

Abstract. Climate change is projected to increase the intensity and frequency of extreme climatic events such as tropical cyclones. However, few studies have examined the responses of hydrochemical processes to climate extremes. To fill this knowledge gap, we compared the relationship between stream discharge and ion input–output budget during typhoon and non-typhoon periods in four subtropical mountain watersheds with different levels of agricultural land cover in northern Taiwan. The results indicated that the high predictability of ion input–output budgets using stream discharge during the non-typhoon period largely disappeared during the typhoon periods. For ions such as Na+, NH4+, and PO43-, the typhoon period and non-typhoon period exhibited opposite discharge–budget relationships. In other cases, the discharge–budget relationship was driven by the typhoon period, which consisted of only 7 % of the total time period. The striking differences in the discharge–ion budget relationship between the two periods likely resulted from differences in the relative contributions of surface runoff, subsurface runoff and groundwater, which had different chemical compositions, to stream discharge between the two periods. Watersheds with a 17–22 % tea plantation cover showed large increases in NO3- export with increases in stream discharge. In contrast, watersheds with 93–99 % forest cover showed very mild or no increases in NO3- export with increases in discharge and very low levels of NO3- export even during typhoon storms. The results suggest that even mild disruption of the natural vegetation could largely alter hydrochemical processes. Our study clearly illustrates significant shifts in hydrochemical responses between regular and typhoon precipitation. We propose that hydrological models should separate hydrochemical processes into regular and extreme conditions to better capture the whole spectrum of hydrochemical responses to a variety of climate conditions.

Predicting the impact of land management decisions on overland flow generation: Implications for cesium migration in forested Fukushima watersheds

The effects of land use and land cover (LULC) change on environmental systems across the land surface's “critical zone” are highly uncertain, often making prediction and risk management decision difficult. In a series of numerical experiments with an integrated hydrologic model, overland flow generation is quantified for both present day and forest thinning scenarios. A typhoon storm event in a watershed near the Fukushima Dai-ichi Nuclear Power Plant is used as an example application in which the interplay between LULC change and overland flow generation is important given that sediment-bound radionuclides may cause secondary contamination via surface water transport. Results illustrate the nonlinearity of the integrated system spanning from the deep groundwater to the atmosphere, and provide quantitative tools when determining the tradeoffs of different risk-mitigation strategies.

The Relationship between the Typhoon Storm in Fujian and Circulation Circumstances

The cases of landing and impact of the heavy rain of typhoon in Fujian are analyzed. From the research of the mainly weather systems which caused heavy rain and the distribution characteristics of atmospheric circulation situation field, we conclude that on the basis of Fujian special geographical location and terrain, there are four types (easterly jet, warm-type sheer, inverted V-shaped trough of typhoon, westerly trough) are conductive to the circulation patterns of causing the heavy rain of typhoon. Through studying a number of typical model cases of heavy rain of typhoon, we can reveal the mechanism which causes the heavy rain of typhoon by the mostly influencing systems in different circulation backgrounds and the causes of the heavy rain of typhoon.